The investigators propose to analyze tendencies of respondents to the Health and Retirement Study (MRS) for nonresponse and response errors in answering related questions, as well as across the instrument as a whole. They aim to learn whether certain types of respondents tend to systematically provide inaccurate or incomplete information. They aim to improve the ability of researchers to use the MRS while recognizing that some respondent records are incomplete and possibly error ridden. They will explore the extent to which data quality problems can be mitigated by modifying the design of the questionnaire. Although this research focuses on the MRS, the theme of taking the respondent as the unit of analysis for study of data quality has general applicability in survey research.